The monoclonal antibody SOX11-C1 (C1) recognizes human Sox11. The transcription factor Sox11 is a member of the SOX (sex determining region Y-related HMG (High Mobility Group) Box) family of proteins. Under normal conditions Sox11 is expressed in the developing central nervous system during embryogenesis and has sequence homology to Sox4. Sox11 plays a role in neuronal maturation and epithelial-mesenchymal interactions and is required for the survival of neuronal and mesenchymal progenitor cells. Sox11 is expressed in mantle cell lymphoma (MCL) and in subsets of hairy cell leukemias, Burkitt lymphomas, and B cell lymphoblastic leukemias, but is not expressed in other B cell lymphomas or in normal B lymphocytes. Sox11 is also expressed in epithelial ovarian cancer and gliomas.